(a) Field
This invention generally relates an electricity generation device generating an induced electromotive force using up and down vibration.
(b) Description of the Related Art
A portable electricity generation device generating electricity using some movements such as human's walking has been known to public.
For example, Japanese Patent Application Publication No. 2008-543254 and Japanese Patent Application Publication No. 2004-159407 disclose vibration electricity generation devices generating an induced electromotive force by up and down vibration of a movable unit provided with a magnet with respect to a fixed unit provided with a coil.
In these vibration electricity generation devices disclosed in the aforementioned patent publications, the fixed unit has a pair of guide shafts extending in the up and down direction and the movable unit is slidably mounted on the guide shafts.
In the vibration electricity generation device of Japanese Patent Application Publication No. 2008-543254, the movable unit is supported on the fixed unit in a suspend ed manner via a pair of coil springs to vibrate in the up and down direction by elastic deformation of the coil springs.
In the vibration electricity generation device of Japanese Patent Application Publication No. 2004-159407, the guide shafts respectively have coil springs on both upper and lower ends thereof. The movable unit vibrates in the up and down direction by elastic rebound of the two sets of the upper and lower coil springs.